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Pain Management

 

Spinal and Joint Injections

In many cases of chronic back pain, spinal injections are used both to learn more about what is causing your pain and to treat your pain. Health care providers refer to these two separate uses of spinal injections as diagnostic and therapeutic. The injections can be a diagnostic tool because they give your doctor information that helps him or her make a diagnosis. For example, if an injection provides pain relief in the area that is injected, it is likely that this particular area is the source of the problem. Once the location of one or more sources of pain is discovered, your health care provider can perform other necessary tests to try to determine the actual problem and create the proper treatment plan. The injections are therapeutic in that they can provide temporary treatment and pain relief.

What medications are injected and why?

With most spinal injections, a local anesthetic (numbing medication) called lidocaine, also known as Xylocaine, is injected into a specific area of the spine. Lidocaine is a fast-acting drug, but the effects wear off within about two hours. Therefore, this medication is used more as a diagnostic tool rather than as a long-lasting pain reliever. Another type of anesthetic, called Bupivacaine, also known as Marcaine, can also be used. This anesthetic takes longer to take effect, but it also wears off slower, giving the patient some relief from pain.

A strong anti-inflammatory steroid medication, cortisone, is also commonly injected along with one of the above anesthetics in order to reduce inflammation in the affected areas. Cortisone is long-lasting and can be slow-releasing in order to give the best possible benefits of pain relief. Cortisone may take several days to begin working to reduce inflammation following injection, but the effects can last for months. In some cases, a narcotic medication such as morphine or fentanyl may be mixed with the cortisone and the anesthetic in order to improve pain relief.

Types of Injections and Why They Are Done

Epidural Steroid Injection:

An epidural steroid injection (ESI) is a common type of injection that is given to provide relief from lower back pain and from certain types of neck pain. The epidural space is the space between the spinal sac (called the dura mater) and the inside of the bony spinal canal. It runs the entire length of your spine. Once injected into this area, the medication moves freely up and down the spine to coat the nerve roots and the outside lining of the facet joints of the spine near the area of injection. For example, if the injection is done in the lumbar spine, the medication will usually affect the entire lower portion of the spine.

There are three different ways to perform an epidural injection:

  • Caudal Block: A caudal block is placed through the sacral gap (a space near the sacrum and below the lumbar spine), into the epidural space. This type of block usually affects the spinal nerves that are at the end of the spinal cord near the sacrum (near the bottom). This collection of nerves is also called the cauda equina. One of the benefits of this type of injection is less chance of a dural puncture, also called a "wet tap." As mentioned above, the dura mater is the spinal sac, the membrane that holds the spinal fluid and protects the cord and nerves from damage.
  • Translumbar: The most common way of performing an epidural is the translumbar approach. This type of injection is performed by placing a needle between two vertebrae from the back. The needle is inserted between the spinous processes of the two vertebrae. You can usually feel the bumps that make up the spinous process by simply feeling the back of your spine.
  • Transforaminal: This type of injection is a very selective injection around a specific nerve root. It is most often used for diagnostic purposes, and it is commonly used in the neck. The foramina are the small openings between your vertebrae through which the nerve roots exit the spinal canal and enter the body. By injecting medication only around a specific nerve root, the doctor can determine if this is the nerve root causing the problem.

Indications to use an epidural:

It may be necessary to have several epidural injections in a series over a period for a few weeks. This is because the relief from the epidural injection decreases with time. It is not uncommon to have three lumbar epidural injections, each about ten days apart.

Epidural injections are good for reducing radicular pain caused by nerve irritation from herniated discs and spinal stenosis. A herniated disc occurs when pressure to a disc's outer fibers (annulus) is so great that it rips, and the nucleus ruptures out of its normal space. If it rips near the spinal canal, the bulging disc can push out of its space and into the spinal canal, placing inappropriate pressure on the spinal cord and nerve roots. Spinal stenosis is basically a narrowing of the entire spinal canal, which places pressure on the nerves and spinal cord. The injections are also helpful when the main problem is arthritis of the facet joints in multiple areas. The medication coats the outside of the joints at multiple levels and is absorbed into the joint. This reduces the inflammation inside the joint.

Risks:

With any surgery, there is a risk of complications. When surgery is done near the spine and spinal cord these complications (if they occur) can be very serious. Complications could involve subsequent pain and impairment and the need for additional surgery. You should discuss the complications associated with surgery with your doctor before surgery. The list of complications provided here is not intended to be a complete list of complications and is not a substitute for discussing the risks of surgery with your doctor. Only your doctor can evaluate your condition and inform you of the risks of any medical treatment he or she may recommend.

Dural Puncture: A dural puncture ("wet tap") is perhaps the most common complication from an ESI. This complication only occurs in 0.1 to 5 percent of all injections. The result of a dural puncture is usually a spinal headache and nausea. A spinal headache occurs when the puncture in the spinal sac fails to seal itself off. This allows the spinal fluid to continue to leak out and lowers the spinal fluid pressure in the brain. When sitting, the headache and nausea are much worse, because the spinal fluid pressure is lower at the top, near your head, than at the bottom of the spine. The headache usually goes away when you lie down with your feet higher than your head. To treat a spinal headache, a "blood patch" is usually recommended. If the doctor realizes immediately during the procedure he has a wet tap, he may perform a blood patch before he removes the epidural needle. A blood patch is a simple procedure in which about three ounces of blood are drawn from an arm vein and immediately injected into the epidural space with an epidural needle. The blood then clots around the spinal sac and stops the leak by forming a "patch."

Intravascular Injection: There is a small chance that the medication may be injected into one of the small blood vessels that run through the epidural space instead of the epidural space itself. This can cause seizures, cardiac arrest, and even death if too much of the medication goes directly into the blood stream. The chance of this happening is very low. Your doctor can discuss it with you in further detail.

Infection: Epidural injections are done under sterile conditions very similar to surgery. Still, anytime a needle is inserted into the body there is a small chance of infection. Since the needle in an epidural is going near the spine, an infection is much more serious if it occurs. The chance that an infection will occur is extremely small.

Bleeding: An epidural injection can result in a hematoma. A hematoma is simply a collection of blood due to an injury to a blood vessel. An epidural hematoma can be serious if it is big enough to cause enough pressure on the spinal nerves so that they quit working. This can cause problems with the bowels and bladder.

Bladder Dysfunction: Because the epidural injection actually paralyzes the nerves to the bowel and bladder for a short period, you may not have control over your bladder for one to two hours.

Neurologic Complications: There is always a small risk of damage to the spinal nerves. The spinal cord is a bundle of millions of nerves that connects the brain with the rest of the body. If the epidural needle directly injures the spinal nerves, this can cause serious neurologic problems.

Facet Joint Injections

Facet joint injections are used to localize and treat low back pain that is caused by problems of the facet joints. These joints are located on each side of the vertebrae; they join the vertebrae together and allow the spine to move with flexibility. The facet joint injections form a pain block that allows the doctor to confirm that it is a facet joint causing the pain. The medication used also decreases inflammation of the joint that occurs with arthritis and joint degeneration.

To insure that an injection is actually into the facet joint, "fluoroscopy" can be used to confirm that the needle is in the right position before the medication is injected. A fluoroscope uses X-rays to show a TV image, so the doctor can watch as the needle is placed into the joint. The fluoroscope can also magnify the image, increasing accuracy.

There are two types of facet joint injections:

  • Interarticular: This is injected directly into the joint to block the pain and reduce inflammation.
  • Nerve Blocks: These help determine whether the joint is indeed a source of pain by blocking the medial branch or the nerves that connect with the joint.

Indications to use a facet joint injection:

A facet joint injection is perhaps the best way to diagnose facet joint syndrome. Joints that may look abnormal on an X-ray may in fact be painless, and joints that look fine may indeed be the source of the pain; only the injection tells the true story. These injections may be used to treat low back pain and determine whether the facet joints are the true culprits. It is also a rather simple procedure with low risk.

Sacroiliac Joint Injections

Sacroiliac (SI) joint pain is easily confused with back pain from the spine. The SI joint is located between the sacrum and the hipbone. In some cases, injecting the SI joint with lidocaine may help your doctor determine whether it is the source of pain or not. If the joint is injected and your pain does not go away, it is probably coming from somewhere else. If the pain goes away immediately, your doctor may also inject cortisone into the joint before removing the needle. The cortisone is added to treat the inflammation from the SI joint arthritis that may be causing your pain. The cortisone injection usually gives temporary relief for several weeks or months.

Indications to use a sacroiliac joint injection:

SI joint injections can be used to prove that the SI joint is the source of pain and subsequently to treat that pain. This injection usually requires the use of fluoroscopic guidance or a CAT scan (computed axial tomography scan) in order to make sure the needle is placed correctly in the joint. CAT scans are X-ray tests that produce X-ray slices taken of the spine, so each section can be examined separately.

Differential Lower Extremity Injections

Various types of injections into certain areas of the lower extremities can help your doctor decide where the pain is most likely coming from. Pain that comes from problems with the back and the spinal nerves can mimic many other conditions. Sometimes it is impossible to tell if the pain you are experiencing is due to a back condition or from a problem in your hip, knee, or foot. To try to determine whether the joint is causing your pain or not, your doctor may suggest injecting medication such as lidocaine into the joint to numb the area. Once the medication is injected, if the pain goes away immediately, it is likely that that joint - not your back - is the source of the pain.

Hardware Injections

At times, your doctor may need to determine whether the metal hardware that has been used during surgery could be contributing to your discomfort. A hardware injection is performed by injecting lidocaine alongside the spinal hardware that was placed in the spine during surgery. If the pain is relieved temporarily by the injection, it may indicate that the hardware is contributing to your pain and whether it needs to be surgically removed.

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